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Author Topic:   Genuine Puzzles In Biology?
frako
Member (Idle past 306 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 91 of 153 (592101)
11-18-2010 4:47 PM
Reply to: Message 78 by Dogmafood
11-07-2010 8:24 AM


Re: Ophiocordyceps
There are other virus that effect rats in such a way as to increase it's chances of being eaten by a cat
I have seen that the virus makes the rat like the cat insted of running away in fear, the virus can also infect humans though what efect if any it has on our minds is not known.

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Akhlut
Junior Member (Idle past 4698 days)
Posts: 6
From: Illnois, US
Joined: 06-16-2010


Message 92 of 153 (594074)
12-01-2010 3:02 PM
Reply to: Message 78 by Dogmafood
11-07-2010 8:24 AM


Re: Ophiocordyceps
Dogmafood What is the prevailing theory about how this fungus evolved the characteristic of controlling it's hosts behaviour in such a specific manner?
Ants have very simple brains and, as such, the fungus only has to utilize a few neurotransmitters of its own manufacture to produce a certain behavior in the ants, such as a compulsion to climb to the highest point nearby. The exact mechanism may not be known at this time (I'm not certain myself; it could be known but I am unaware of it), but it rests on simple neurotransmittor usage on the part of the fungus to get the desired behavior in the ant.
There are other virus that effect rats in such a way as to increase it's chances of being eaten by a cat. I think there is another that effects fish in such a way that they will be eaten by a bird. Could rabies be said to be doing the same type of thing to it's hosts?
First, it's not a virus, it's a parasite, and they do much the same thing as the fungus: affect hormone cascades in the brain. By reducing the emotion of fear in an organism (or by increasing the likelihood of other behaviors), it increases that organism's likelihood of being eaten by the final host of the parasite.
Another question is how does genetic memory or instinct occur?
Alleles that control for the structure of the brain and the release of certain neurotransmittors.
Why am I instinctively afraid of spiders and snakes and heights?
Because your ancestors' relatives who weren't died before they could reproduce.
I see how being afraid of dangerous things is helpful but how do my genes remember that from previous encounters in other generations?
The thing is that they don't remember previous encounters: certain behaviors are "hardwired" into brains by hormone cascades from certain stimuli (think of hunger or how you pull your hand away from a hot stove or a sharp object). Those ancestors of yours who happened to be afraid of snakes and spiders were more likely to survive than their relatives who did not feel such a fear.

This message is a reply to:
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Replies to this message:
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herebedragons
Member (Idle past 858 days)
Posts: 1517
From: Michigan
Joined: 11-22-2009


Message 93 of 153 (594167)
12-02-2010 11:27 AM
Reply to: Message 74 by Stephen Push
11-07-2010 3:24 AM


Re: Animal Cognition & Consciousness
In watching a documentary about sharks, my daughter commented about sharks being evil. I responded that sharks aren't evil, they just do what they do to survive, which in our human minds may appear as evil.
I am doing a study on an invasive species (Glossy Buckthorn) here in Michigan and might be able to make a case that this plant is evil. But it is just doing what it is adapted to do ... survive and thrive.
Many organisms have detrimental effects upon the environment, but humans seem to be the species that is aware of its impact and morally and ethically driven to remedy the problem.
Definitions are part of the problem. Researchers in this field often have different definitions of what they mean by consciousness. We don't even understand consciousness in humans, so it's probably not possible at this stage to understand it in animals.
Is this the type of consciousness that you are refering to ... being aware of our impact upon other organisms and a feeling of moral and ethical responsibilities to those impacts?

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 Message 74 by Stephen Push, posted 11-07-2010 3:24 AM Stephen Push has replied

Replies to this message:
 Message 123 by Stephen Push, posted 12-07-2010 1:16 PM herebedragons has replied

Blue Jay
Member (Idle past 2698 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 94 of 153 (594176)
12-02-2010 12:30 PM
Reply to: Message 82 by Stephen Push
11-07-2010 10:03 AM


Re: Amygdala & Fear
Hi, Stephen Push.
Stephen Push writes:
But our brains appear to be hardwired to recognize images of snakes and spiders.
I study spiders for a living. I don't study arachnophobia or spiders that are dangerous to humans, but I'm familiar enough with the topic and I've been a spectator in this debate for a couple years.
Spider bites can be annoying and painful, and so it makes sense for humans to develop behavioral aversions to them. But, to claim an evolutionary significance for arachnophobia requires spiders to have had a significant impact on human fitness, and I just don't see that as plausible.
  1. The Old World, where humans evolved, doesn't have any spiders that are known to have killed people, and only a handful that are known to cause significant health effects, although these are so uncommonly encountered by humans that bites are almost never reported.
  2. In Asia, where the most dangerous Old World spiders occur, people regularly eat spiders, so I don't see arachnophobia being a major component of human evolution there.
  3. The only spiders known to have caused fatalities (only four taxa) are native to Australia and the Americas.
The best explanation for arachnophobia is as a learned or cultural behavior. But, I have no idea about the causes and explanations for ophidiophobia (fear of snakes).

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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frako
Member (Idle past 306 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 95 of 153 (594179)
12-02-2010 12:46 PM
Reply to: Message 94 by Blue Jay
12-02-2010 12:30 PM


Re: Amygdala & Fear
But, to claim an evolutionary significance for arachnophobia requires spiders to have had a significant impact on human fitness
Well some tribes eat those big spiders, so i think the fobia is more a leraned trait then a genetic one.

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bluescat48
Member (Idle past 4190 days)
Posts: 2347
From: United States
Joined: 10-06-2007


Message 96 of 153 (594204)
12-02-2010 3:23 PM
Reply to: Message 94 by Blue Jay
12-02-2010 12:30 PM


Re: Amygdala & Fear
The best explanation for arachnophobia is as a learned or cultural behavior.
True to a point. If a person associates the outcome from the bites, he might develop a phobia to it, on the other hand I can say for myself it wasn't. I was not arachnophobic before I was bitten by a black Widow, and other that 3 days of agony, there were no other effects and I still am not arachnophobic, 41 years later.

There is no better love between 2 people than mutual respect for each other WT Young, 2002
Who gave anyone the authority to call me an authority on anything. WT Young, 1969
Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008

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Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 97 of 153 (594207)
12-02-2010 3:50 PM
Reply to: Message 95 by frako
12-02-2010 12:46 PM


Re: Amygdala & Fear
Well some tribes eat those big spiders, so i think the fobia is more a leraned trait then a genetic one.
IMO, pattern recognition is hard wired into the most primitive portions of our brain. This is why trout do not have to learn to recognize the shadows of flies as they rest on the surface of a stream. Their brains already know what patterns are food and which are not.
The same for humans. We have patterns associated with danger hard wired into the most primitive portions of our brains. This may be why we call them irrational fears because it overrides the grey matter that evolved in more intelligent species like us.

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Replies to this message:
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New Cat's Eye
Inactive Member


Message 98 of 153 (594215)
12-02-2010 4:51 PM
Reply to: Message 97 by Taq
12-02-2010 3:50 PM


Re: Amygdala & Fear
IMO, pattern recognition is hard wired into the most primitive portions of our brain.
I hafta agree. I'm really afraid of snakes.
But I don't even have to see that its a snake. Even just a shape like this...
...can freak me out. Well, not on a computer screen but if you printed that out and put it on the floor by my desk and stumbled across it, then it'd prolly scare me.
The same for humans. We have patterns associated with danger hard wired into the most primitive portions of our brains. This may be why we call them irrational fears because it overrides the grey matter that evolved in more intelligent species like us.
I've been startled by a cord that was coiled up on the floor. Like heart-racing full on fight of flight...
I creeps me out just thinking about it.
For me, the recognition of that pattern definately causes fear.

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 Message 97 by Taq, posted 12-02-2010 3:50 PM Taq has replied

Replies to this message:
 Message 99 by Taq, posted 12-02-2010 5:02 PM New Cat's Eye has replied

Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 99 of 153 (594220)
12-02-2010 5:02 PM
Reply to: Message 98 by New Cat's Eye
12-02-2010 4:51 PM


Re: Amygdala & Fear
I hafta agree. I'm really afraid of snakes.
But I don't even have to see that its a snake. Even just a shape like this...
Me too. I was raking up leaves one time and somehow spun a wheel on an upturned skateboard. It was one of the old style with the bb's for bearings that make this rasping sound. The rustling sound made by the spinning wheel and the bb's rattling around in the wheel sent me into immediate panic mode. My heart rate went from 70 to 200 within seconds. After I calmed down a bit I laughed my ass off, but there was no laughing for about 5 seconds.

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Replies to this message:
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New Cat's Eye
Inactive Member


Message 100 of 153 (594221)
12-02-2010 5:11 PM
Reply to: Message 99 by Taq
12-02-2010 5:02 PM


Re: Amygdala & Fear
The rustling sound made by the spinning wheel and the bb's rattling around in the wheel sent me into immediate panic mode. My heart rate went from 70 to 200 within seconds. After I calmed down a bit I laughed my ass off, but there was no laughing for about 5 seconds.
Yeah, afterwards you really feel stupid... because of how strongly you react.
But I've never scared myself from a noise I caused. Though, my hearing is poor. And my eyes are good.
What about you? Maybe bad eyes and good hearing? Could we just rely more on our strongest sense for the pattern recognition?

the spinning wheel and the bb's rattling around in the wheel
they're called "bearings"

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William Rea
Junior Member (Idle past 2621 days)
Posts: 12
Joined: 12-23-2007


Message 101 of 153 (594340)
12-03-2010 1:51 AM


Everything Is!
I was and still am more inclined to Physics and Mathematics and had very little interest in Biology during my education so everything in Biology is a genuine puzzle for me!
I can dip into most of the threads in this forum and I will have learnt something new by the time I have read through to the end.
That is genuinely "awesome" and perhaps something our more theocratically aligned fellow members should thank the forum for.

Replies to this message:
 Message 105 by Dr Adequate, posted 12-03-2010 12:11 PM William Rea has replied

Dogmafood
Member (Idle past 349 days)
Posts: 1815
From: Ontario Canada
Joined: 08-04-2010


Message 102 of 153 (594361)
12-03-2010 8:21 AM
Reply to: Message 92 by Akhlut
12-01-2010 3:02 PM


Re: Ophiocordyceps
Thanks for the reply Akhlut.
I realize that most of my questions are only a genuine puzzle to me. I think what bewilders me the most is trying to imagine the circuitous evolutionary route that this fungus has taken.
Is there evidence that we actually have instinctive fears? I recall a study that showed children are naturally wary of heights but I wonder if fear of snakes and spiders are not a learned behavior. I have taught my kids not to be afraid of the little critters but I can't remember what their initial reaction to them was.
A little off topic perhaps but if our behavior and choices are a result of hormone floods and chemical reaction to stimuli what room does this leave for the concept of 'free will'? Why do I like vanilla ice cream? Why do I find my wife attractive?

This message is a reply to:
 Message 92 by Akhlut, posted 12-01-2010 3:02 PM Akhlut has replied

Replies to this message:
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Larni
Member (Idle past 164 days)
Posts: 4000
From: Liverpool
Joined: 09-16-2005


Message 103 of 153 (594367)
12-03-2010 8:36 AM
Reply to: Message 91 by frako
11-18-2010 4:47 PM


Toxoplasma Gondii
I have seen that the virus makes the rat like the cat insted of running away in fear, the virus can also infect humans though what efect if any it has on our minds is not known.
That's Toxoplasma Gondii. It's pretty much endemic to humans and make men become grumpy curmudgeons and women promiscuous. It is also implicated in schizophrenia (but this is debated at this point in time).

This message is a reply to:
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Akhlut
Junior Member (Idle past 4698 days)
Posts: 6
From: Illnois, US
Joined: 06-16-2010


Message 104 of 153 (594422)
12-03-2010 12:07 PM
Reply to: Message 102 by Dogmafood
12-03-2010 8:21 AM


Re: Ophiocordyceps
Dogmafood Thanks for the reply Akhlut.
No problem.
I realize that most of my questions are only a genuine puzzle to me. I think what bewilders me the most is trying to imagine the circuitous evolutionary route that this fungus has taken.
Without the time to do the research, my main hypothesis is that it was once a surface parasite (their equivalent to athlete's food), that eventually started releasing poisons into the ant to try to eliminate its immune response and happened to hit upon several neurotransmittor analogues that altered its behavior. I don't know if that is what, in fact, occurred, but it seems likely to me.
Is there evidence that we actually have instinctive fears? I recall a study that showed children are naturally wary of heights but I wonder if fear of snakes and spiders are not a learned behavior. I have taught my kids not to be afraid of the little critters but I can't remember what their initial reaction to them was.
Well, there's evidence that other animals have instinctive fears. For instance, you can condition rats to be fearful of brightly-lit areas (mild electric shocks in a brightly-lit cage) and you can condition monkeys to be fearful of snake-like objects (flexible tubing, for instance, by showing a video of a monkey eliciting a fear response in proximity to the tubing). However, you cannot make a rat fearful of dark places or monkeys fearful of arbitrary objects (rocks or trees). This is because certain things are naturally hardwired as being "always good" for certain animals: rats typically don't like bright areas anyway because they're small, nocturnal prey animals, but they conversely like dark areas for that same reason. Monkeys don't like snakes because they can eat them, but they like trees because they live there.
I imagine it is similar for humans: it isn't an automatic phobia, but a predisposition for becoming fearful in response to stimuli that leads to phobia (being bitten by a snake or being told how dangerous they are).
A little off topic perhaps but if our behavior and choices are a result of hormone floods and chemical reaction to stimuli what room does this leave for the concept of 'free will'? Why do I like vanilla ice cream? Why do I find my wife attractive?
It's a tricky question that I honestly don't have any ideas about. While it's easy to say that a mosquito has little in the way of free will, for large-brained, complex animals like mammals, birds, some reptiles, and cephalopods, it is entirely different and perhaps unknowable. While some simple preferences (food) are easy to say why we like them (fatty foods were great when we didn't have such reliable agriculture to keep us fed at all times), and even some more complex ones are relatively easy to answer (we find our mates attractive because of a combination of physical attraction and attitudes compatible with our own, which means optimal reproduction and survival of offspring), there is still the problem of trying to figure out how much is within our conscious control versus instinctual or environmentally produced phenomena.
So, to that end, I'm not sure how much I'd worry about how much of my preferences are determined by hormone cascades and genetic influence.

This message is a reply to:
 Message 102 by Dogmafood, posted 12-03-2010 8:21 AM Dogmafood has not replied

Dr Adequate
Member (Idle past 285 days)
Posts: 16113
Joined: 07-20-2006


Message 105 of 153 (594424)
12-03-2010 12:11 PM
Reply to: Message 101 by William Rea
12-03-2010 1:51 AM


Re: Everything Is!
Have we met on the JREF forums? Your name seems familiar somehow.

This message is a reply to:
 Message 101 by William Rea, posted 12-03-2010 1:51 AM William Rea has replied

Replies to this message:
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